An automatic injection apparatus is a device which enables an individual to self-administer fluid medication by simply triggering the apparatus. The apparatus contains a measured dose of medication in a sealed sterile condition and is capable of storing the medication for an extensive period of non-use. The apparatus administers the self-contained dose automatically, so that the user does not need to visually insert the needle into his/her own tissue or depress a plunger, such as in a common syringe.
Automatic injectors are particularly advantageous in emergency conditions. Such injectors can carry: antidotes for nerve gas for use during emergency chemical warfare conditions; insulin for diabetes; epinephrine for allergic reactions; or analgesics.
An automatic injector apparatus commonly includes an elongated tubular casing and a medicine "container". The medicine container contains a dose of fluid medication. Also included is a needle for injecting the medication into the user. The injector further has a trigger mechanism which causes the needle to penetrate the user's tissue and inject the medication from the container.
Typical automatic injection apparatuses have a drawback in that they administer a single, one-time dose of medication and are not reusable. After this single use, the entire apparatus is discarded. This results in high cost and waste.
Another drawback is the relatively short storage life of some of medications. The storage life of a medication is generally less than the useful life of the automatic injection apparatus. Automatic injectors are expected to be stored for long periods of time, often 1-2 years or more. Unfortunately, many medications do not have a comparable storage life. For example, some medications have storage lives of only approximately six months or less. The medicine could thus become ineffective before the injector is used, resulting in the wasteful disposal of unused injection apparatuses. This also contributes to high costs.
The inability of automatic injection apparatus to be reloaded causes substantial addition costs in other ways. Storage of integrated one use automatic injections is made more complicated and stock must be carefully inventoried and tracked for dates of use. Medicines needing or best stored under particular conditions (refrigeration) are typically unavailable due to the bulk of the injection apparatus. Medicines used in automatic emergency injectors are also inventoried in addition to inventories of medications used in hospitals. These factors become particularly troublesome and costly for the military because of the logistical problems, storage considerations, and tremendous quantities involved.
Another very serious limitation is that prior automatic injectors are not capable of manual injection in instances where they fail. Prior injectors are manufactured as a single, integrated system that provides one application of medicine, and is then discarded. However, if the trigger, firing or other mechanism fails and the injection is not administered, the user cannot get to the medication contained within the sealed unitary casing. The internal components are also not capable of being used manually. Thus the injectors pose a risk that due to mechanical failure medication will not be capable of administration.
This invention provides an automatic injection apparatus in which the injection apparatus can be loaded just prior to use. The injection apparatus can be loaded with a variety of medications as needed for the particular situation, and can later be reloaded to refreshen the medication or change medications. The apparatus can be reloaded numerous times with cartridges commonly used in hospital inventories so that duplicate inventories are not required and better storage conditions are possible. As individual cartridges are used or the medicine contained therein becomes ineffective, the user simply replaces the cartridge with a new one without disposing of the injector. In this manner, only the inexpensive cartridges are replaced, and not the entire apparatus. This reduces the costs significantly. Furthermore, the injector allows access and removal of a syringe subassembly by the user. The syringe subassembly can be used to provide a manual injection in the event that the injector or cartridge fails, or in the event that the user simply desires to apply the injection manually. The described system also includes embodiments which have dual dose capability for second dose administration either automatically injected or manually injected.